/*

 * Licensed to the Apache Software Foundation (ASF) under one

 * or more contributor license agreements.  See the NOTICE file

 * distributed with this work for additional information

 * regarding copyright ownership.  The ASF licenses this file

 * to you under the Apache License, Version 2.0 (the

 * "License"); you may not use this file except in compliance

 * with the License.  You may obtain a copy of the License at

 *

 *     http://www.apache.org/licenses/LICENSE-2.0

 *

 * Unless required by applicable law or agreed to in writing, software

 * distributed under the License is distributed on an "AS IS" BASIS,

 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.

 * See the License for the specific language governing permissions and

 * limitations under the License.

 */

package com.bff.gaia.unified.sdk.fn.windowing;



import com.google.auto.value.AutoValue;

import com.bff.gaia.unified.sdk.coders.AtomicCoder;

import com.bff.gaia.unified.sdk.coders.CoderException;

import com.bff.gaia.unified.sdk.transforms.windowing.BoundedWindow;

import com.bff.gaia.unified.sdk.util.VarInt;

import com.bff.gaia.unified.vendor.grpc.v1p13p1.com.google.protobuf.ByteString;

import com.bff.gaia.unified.vendor.guava.com.google.common.io.ByteStreams;

import org.joda.time.Instant;



import java.io.IOException;

import java.io.InputStream;

import java.io.OutputStream;



/**

 * An encoded {@link BoundedWindow} used within Runners to track window information without needing

 * to decode the window.

 *

 * <p>This allows for Runners to not need to know window format during execution.

 */

@AutoValue

public abstract class EncodedBoundedWindow extends BoundedWindow {

  public static EncodedBoundedWindow forEncoding(ByteString encodedWindow) {

    return new AutoValue_EncodedBoundedWindow(encodedWindow);

  }



  public abstract ByteString getEncodedWindow();



  @Override

  public Instant maxTimestamp() {

    throw new UnsupportedOperationException(

        "TODO: Add support for reading the timestamp from " + "the encoded window.");

  }



  /**

   * An {@link Coder} for {@link EncodedBoundedWindow}s.

   *

   * <p>This is a copy of {@code ByteStringCoder} to prevent a dependency on {@code

   * unified-java-sdk-extensions-protobuf}.

   */

  public static class Coder extends AtomicCoder<EncodedBoundedWindow> {

    public static final Coder INSTANCE = new Coder();



    // prevent instantiation

    private Coder() {}



    @Override

    public void encode(EncodedBoundedWindow value, OutputStream outStream)

        throws CoderException, IOException {

      VarInt.encode(value.getEncodedWindow().size(), outStream);

      value.getEncodedWindow().writeTo(outStream);

    }



    @Override

    public EncodedBoundedWindow decode(InputStream inStream) throws CoderException, IOException {

      int size = VarInt.decodeInt(inStream);

      ByteString encodedWindow = ByteString.readFrom(ByteStreams.limit(inStream, size));

      return EncodedBoundedWindow.forEncoding(encodedWindow);

    }



    @Override

    public boolean consistentWithEquals() {

      return true;

    }



    @Override

    public boolean isRegisterByteSizeObserverCheap(EncodedBoundedWindow value) {

      return true;

    }



    @Override

    protected long getEncodedElementByteSize(EncodedBoundedWindow value) throws Exception {

      return (long) VarInt.getLength(value.getEncodedWindow().size())

          + value.getEncodedWindow().size();

    }

  }

}